GLENDALE, Ariz. – Lucas Giolito and Reynaldo Lopez made it to the White Sox roster last season. Top prospect Michael Kopech figures to land sometime this summer. Former first-round picks Carlos Rodon and Carson Fulmer remain in the mix.

With James Shields’ contract expiring after this season, it won’t be long until youth is served throughout the Sox’s rotation.

It starts with Giolito and Lopez, both of whom came to the Sox from Washington in the Adam Eaton trade after the 2016 season.

Both excelled at Triple-A Charlotte before earning late-season promotions. Each pitcher went 3-3 in limited rotation duty, Giolito having a 2.38 ERA in seven starts and Lopez with a 4.72 ERA in eight starts.

Manager Rick Renteria has noticed a difference between the duo’s demeanor a year ago and today.

“Their confidence is pretty high. They have a quiet confidence about them, a belief that they belong here,” Renteria said Saturday.

That wasn’t always the case for Giolito, a first-round selection in 2012 who sailed through the minors until being hit hard in four starts for Washington in 2016, when he had a 6.75 ERA.

Over the course of his 2017 season at Charlotte, the 23-year-old right-hander figured out how to believe in himself again, and carried it over to his big league return.

“It started in spring training last year, really trying to improve myself,” Giolito said. “I just wanted to relax, have fun with it, stop putting so much pressure on myself and enjoy the game and enjoy the process of getting better.

“Once I started buying into that I started stringing together good starts, built confidence and was able to go out and trust whatever I had that day,” he said.

Like Giolito, Lopez had some big league time with the Nationals in 2016, but took a big step forward last season with the Sox.

“I feel happy and proud. Now I have a spot. The trade was great for my career because I now have this opportunity,” Lopez said through a translator.

“I learned hitters are looking for a specific pitch in a specific spot, you have to adjust your plan to get the result that you want. It was a good learning process for me last year,” he said.

Not far behind Giolito and Lopez is Kopech. The biggest power arm in camp at Camelback Ranch and one of the top prospects in baseball, Kopech has also had to learn to adjust after a 50-game drug suspension in July 2015 and a broken hand at 2016 spring training with the Boston Red Sox.

Still just 21, Kopech rebounded with a big season, striking out 172 in 1341/3 innings over 22 starts at Double-A Birmingham and three more at Charlotte.

Along the road back, Kopech discovered meditation was a key to preparing for each start.

“It was definitely the toughest thing I’ve had to do,” he said of the suspension. “But I became more mindful as an athlete and an even harder worker. For me, that span of not playing really put things into perspective.”

“I was doing it before every start, then I realized how beneficial it was for me personally, and I kept doing it through the offseason.”

Beyond Shields and veterans Hector Santiago and Miguel Gonzalez, who are back with the Sox to help with the innings load until Kopech and friends are ready, the Sox still have Rodon and Fulmer.

Rodon, at 25 the old hand among the next generation, never really got going last season. After missing spring training because of an arm issue, the left-hander only made 12 starts, posting a 4.15 ERA before being shelved in September. He had shoulder surgery, but is on a throwing program and hopes to be back sometime in the first half of the season.

He, too, has had to learn patience.

“I kind of know what to expect now,” Rodon said. “I maybe forced the issue and went a little too quick last year.”

So far, Rodon said, “Everything’s free and easy” with his program.

Fulmer struggled in his big league debut in 2016, just over a year after being drafted in the first round. But a trip to the minors last year helped and he also made a strong return to the Sox, going 3-1 with a 3.86 ERA in five starts.

He figures to be in the rotation at least until Rodon returns or Kopech is promoted, but says he will be ready for whatever role he’s asked to fill as his confidence also gained from a year ago.

“That was the thing I needed to make that jump,” he said. “It’s going to be nice to build off that.”

Rodon, in his fourth spring training camp, is impressed by what he has seen from his fellow pitchers.

“All these guys are pretty mature,” he said. “This is a really good group of guys. It’s going to be awesome.”